The present invention relates to an electronic device and particularly an on-vehicle module provided with a board having through-holes to which pin terminals (wiring pins and connector pins) of another substrate or module are connected in a press-fit manner.
Recently, as a connection form in case where components are mounted on a board in which electrical wiring is formed, the press-fit connection is increasingly being adopted in which as shown in FIG. 1A a plurality of pin terminals 1 mounted in a press-fit connector 3 of a component are press-fit into a plurality of through-holes 8 formed in a board 4 so that the pin terminals 1 are mechanically connected to wiring in the through-holes 8 to thereby make electrical connection therebetween. Since an outer diameter of a connection part 2 of each pin terminal 1 is larger than an inner diameter of each through-hole and the connection part is resiliently deformed by external force, the outer diameter of the connection part of the pin terminal 1 is reduced by the through-hole when the pin terminal 1 is press-fit into the through-hole and at the same time the restoring force of the connection part acts to expand the pin terminal. Consequently, the surface of the connection part of the pin terminal comes into mechanical contact with the wiring in the through-hole as shown by a sectional photograph of FIG. 1B to thereby make electrical connection therebetween as shown in FIGS. 1A and 1B as an example of the press-fit connection.
The following is being studied about the press-fit connection. For example, in JP-A-2005-268422 and JP-A-2006-86428, in order to cope with the problem that plating formed at the surface of the pin terminal comes off to short circuits on a board when the pin terminal is press-fit into the through-hole, an entrance part at a press-fit end of through-hole is chamfered to thereby prevent plating from scraping off. In JP-A-2006-140383, in order to cope with scraping off or whitening occurring in a board by restoring force of pin terminal when the pin terminal is press-fit into a through-hole, a buffer member is disposed at an entrance of the through-hole of the board to deform a connection part of the pin terminal by the buffer member before the connection part of the pin terminal is press-fit into the through-hole, so that scraping off or whitening of the board is prevented.